Airless paint spraying advice

[Jeremy Harris]

I found that there were no fumes or smell, and although I wore a dust mask I'm not convinced it was essential.  When I've sprayed using a conventional compressed air spray gun there has always been a visible mist in the air.  With this system there is nothing visible in the air at all, as long as you're painting right in the sweet spot where the gun is square to the wall and at the right distance from it.  The dust that was generated was solely from times when the gun was at a wonky angle, like getting paint into corners, where the distance inevitably varied a bit.

 

The technique is the same as with any other spray gun, long straight runs, bending your wrist as you go to keep the gun perpendicular to the surface, and stopping the spray at the start and end of each run.  To get a good finish it seems best to have the spray pattern set to vertical first, and do a series of overlapping horizontal passes, then rotate the nozzle to get a horizontal pattern and go over the painted area again with vertical passes.

 

I found that the real need to wear a Tyvek suit wasn't from the spraying, but from mixing the paint up  and cleaning the kit afterwards.  Cleaning is messy, as you have to flush a bucket of clean water through the pump and gun, with another bucket to catch all the waste.  Inevitably this makes a bit of a mess.

Edited July 13, 2017 by JSHarris

[Alexphd1]

quick question Jeremy, did you store the sparyer pump armour in it?

[Jeremy Harris]

On 15/08/2017 at 21:28, Alexphd1 said:

quick question Jeremy, did you store the sparyer pump armour in it?

 

 

Sorry, missed this earlier.  I'm not sure exactly what you mean by "pump armour". 

 

My unit is pretty basic, just a motor driven high pressure pump, a high pressure hose and a pretty simple spray gun.

 

Storing the unit after use is really just a matter of cleaning it out very thoroughly, and making sure it's well lubricated (mine came with a bottle of lubricant).  When new, they are supplied with the pump unit partially filled with some sort of preservative, that smelt very like white spirit to me.  There's nothing in the instructions for mine about adding something like this for long term storage, though.  Having said that, it would be pretty easy to partially dismantle the pump and make sure it was clean and dry inside, and maybe fill it with something like a dilute oil/white spirit mixture, just to make sure nothing corrodes whilst it's in storage.

 

 

[Pete]

Yes.I always store mine with pump armour in it. Apparently it stops the seals drying out and corrosion on the pump parts. (Mine is a Graco airless sprayer)

[Jeremy Harris]

So, "pump armour" is the preservative/anti-corrosion stuff that's in the pump when new, is it?

 

The instructions for mine just say that the pump is supplied with a "mineral spirit preservative" that has to be flushed out well before first use, but there's no mention of using this for long term storage.  As above, I had thought of doing this, using a home made mixture, but I'll go and investigate what this "pump armour" stuff is.  If it turns out to be what I think it is, then I'll probably just make my own.

[Jeremy Harris]

OK, just checked the chemical composition of Graco Pump Armour, and it's 40% to 60% ethylene glycol antifreeze solution, with a tiny amount (0.1% to 1%) sodium nitrite as a corrosion inhibitor.  This is identical to BLUE antifreeze concentrate used in automotive applications, sold as concentrate with between 40% and 60% ethylene glycol.  Often the number in the name of concentrated ethylene glycol antifreeze is the percentage of ethylene glycol used.  AFAICS, all BLUE antifreeze uses a similar formula - concentrated ethylene glycol plus sodium nitrite as a corrosion inhibitor.

[Jeremy Harris]

Further to the above, I've been digging out prices if anyone wants to mix their own pump corrosion inhibitor.  It seems that the Graco Pump Armour is a bit pricey, at around £16 per litre, so it's worth looking at a cheaper option.

 

For those that want to make their own "pump armour", then here's a recipe, using stuff from ebay.  Bear in mind that this will produce the same concentrate as the Graco product, so needs to be diluted in the same way before use.  This is actually a 60% ethylene glycol, ~1% sodium nitrite corrosion inhibitor mix, so near-identical to pump armour, and at least well within their production tolerance, right at the upper end, so it will, if anything, be slightly more effective.

 

Buy 5 litres of 100% ethylene glycol (around £20 from ebay) and 250g of sodium nitrite (also from ebay) for around £5 (this is more sodium nitrite than needed, but it's cheaper to buy 250g).

 

Mix 50g of sodium nitrite to the 5 litres of ethylene glycol and then add 3.3 litres of water and stir well.  You now have 8.3 litres of "pump armour" concentrate, for the princely sum of about £25 (with enough sodium nitrite left over for four more batches).  Dilute and use in the same way as pump armour.  The only differences between pump armour and the above mixture is that pump armour costs over five times more, and this home made version doesn't have the blue dye and bittering agent that's added to stop people drinking the stuff.  Chemically it will do the same thing, and provide the same, or better, level of corrosion protection.

 

If you don't want to bother making the stuff, then buy blue antifreeze concentrate (not the red or purple stuff) and use that.  Any decent brand of blue antifreeze concentrate will be around 40% to 50% ethylene glycol, and will have sodium nitrite as the corrosion inhibitor.  The red or purple antifreeze is not ethylene glycol, and may contain silicates and be based on OATs, so is not suitable for this purpose.  Decent quality blue antifreeze is about half the price of pump armour, so still a significant saving.

Edited August 17, 2017 by JSHarris

[Ferdinand]

Does anyone have any experience of the capabilities of the Wagner airless sprayguns available from the likes of Toolstation and Screwfix?

Screwfix have 4, including both models with a reservoir and direct from the tin.

WAGNER POWER PAINTER 60 - 625W, 7.5l reservoir, Max 0.8l/min, £240. 
WAGNER POWER PAINTER 60 - 750W, No reservoir, 200bar, 10m hose, Max 0,95l/min, £440.

WAGNER CONTROL PRO 250M AIRLESS PAINT SPRAYING UNIT 550W, No reservoir, 110 bar, 9m hose, Max 1.25l/min, £480.

WAGNER POWER PAINTER 90 AIRLESS PAINT SPRAYER 800W, No reservoir, 15m hose, 200 bar, 1.25l/min, £800. On wheels.

 

I have a small bungalow to do (or have done) next week, then subject to a planning application an 18mx30m industrial unit to a height of 4.5m later in the year.

 

The only one with reviews (which are excellent) is the smallest model, which is also the only one sold by Toolstation, also with excellent (almost messianic in some cases) reviews.

 

I am surprised and impressed at how low these prices start. I reckon that the sweet spot may be the £440 or £480 models, to avoid the reservoir. But is there a big difference between 110 bar and 200 bar pressure in use? Presumably the latter has a bigger nozzle to dispense more paint.

Ferdinand

 

Edited September 12, 2017 by Ferdinand

[Alex C]

I bought and used a wagner project pro 119 to paint my house. A great piece of kit to use in an empty house. I will sell mine if you are interested and any where near surrey to pick it up. I think it was about £600 including a better gun and another £40 for a spray tip extension to paint high ceilings. I wouldn't bother with anything smaller as the paint would need thinning too much to get through the nozzle.

[Nickfromwales]

2 hours ago, Alex C said:

I bought and used a wagner project pro 119 to paint my house. A great piece of kit to use in an empty house. I will sell mine if you are interested and any where near surrey to pick it up. I think it was about £600 including a better gun and another £40 for a spray tip extension to paint high ceilings. I wouldn't bother with anything smaller as the paint would need thinning too much to get through the nozzle.

Pop an ad in the 'market place' section here if you want to sell it  

[bassanclan]

I'm wanting to paint 330sqm of external render with an airless spray paint machine, but the render has 6-8mm deep, 12mm wide ashlar grooves in. (Regency spa town style)

 

Will an airless sprayer do the job on its own? Or would I be better painting the ashlar grooves with a brush?

 

As you can see I have already painted the grooves with a primer as they are formed from upvc beads.

[Nickfromwales]

Go over all the grooves with at least one full coat, staying away from the adjacent faces of the render 'blocks'. Once you've been right around all of these aka cutting in is done, go around the perimeter and do the same. 

See how well the beads have covered and coat them again, only if absolutely necessary. 

Do all the fiddly detail work before reloading the machine for the general spray work as when your moving at a pace you really don't want to be arsing around with nooks and crannies . 

[Jeremy Harris]

If you use a small spray tip, then lower the pump pressure a bit, you will easily be able to spray those grooves OK.  My kit came with a 415 tip and a 315 tip, and I would suggest getting a 215 tip for the grooves (they are only about a fiver each).  The first digit is half the width of the spray fan, in inches (so a 415  = 8" pattern, a 215 = 4" pattern, etc) and the second number is the size of the orifice, in thousands of an inch.  I found that a 15 thou orifice seemed fine for pretty much everything.

 

Follow @Nickfromwales advice to do all the grooves first, with a 215 or perhaps 315 tip, then change to a wider tip for the main coat.  I doubt you'll want anything wider than a 415, I found that this was pretty quick, with a wide enough spray pattern to cover a wide area pretty quickly.  In my case the speed of painting was set by how fast I could move around more than the capability of the spray gun; there is a knack to walking along keeping the gun at a constant distance to the wall and perpendicular to it.

[Ferdinand]

I think this is the best place to ask whether there are any recommendations for appropriate respirator masks when doing airless spraying.

 

In my case it will be my maintenance and renovation man, so I want something good. I am thinking about two from Screwfix:

 

One is a 3m Model 4251 at about £20, which seems to be a 28-day and throw away respirator. 100 reviews averaging nearly 5*.

 

The other is also highly rated, and uses replaceable filters, by Reliance, also with a number of reviews averaging nearly 5* .

 

Given that work patterns will be intermittent, a few days here, and a bit more a month or two later, the second seems more appropriate.

 

I do not think I need a full air-fed system for this application. I would welcome guidance, however.

 

Ferdinand

[Jeremy Harris]

Depends what you're spraying, really.  If it's emulsion, or water based paint, then just an ordinary dust mask will be fine, as there won't be any fumes and there's not a lot of dust created either.  If you're spraying oil-based paint or lacquer then a respirator with an appropriate organic solvent cartridge would be a good idea.  Even then I suspect the benefit is small, as the fumes won't be significantly different from applying the paint with a brush or roller.

 

It's easy to think that painting with a spray gun is going to create a fog of paint and fumes, much as older, high pressure, low volume air spray guns used to create.  Because there's no air with one of these guns, the only paint dust is going to be stuff that either doesn't hit the surface (usually because the gun isn't pointed at it) or that bounces back off the surface if the gun is too close, the pressure is set too high or the gun isn't perpendicular to the surface.

 

The spray pattern on one of these airless spray guns is pretty tight, as long as the tip is clean and not worn (they do wear out after a few tens of hours of use).  With practice you can paint without masking anything, just by using a larger version of a painter's george as a mask, held in your free hand.  I found a scrap bit of thin plywood, with a bit of thin, but stiff, plastic sheet, with a nice straight edge, taped to one side worked well.  You can just hold this into a corner and spray away, moving the mask as you move the gun.

 

Decent gloves are essential, as there is a risk of paint getting blown into your skin if you accidentally point the gun at any unprotected part of the body.  It's a bit of a compromise, as thick rubber gloves give good protection from the high pressure spray, but don't allow the dexterity needed.  I ended up using the Port West A320 PU coated gloves.  Not ideal, in terms of giving total protection, and they are porous on the rear surface, but they give good dexterity, and that's a greater safety benefit in my personal view.

Edited September 18, 2017 by JSHarris

[Nickfromwales]

If the same person will be using the mask ONLY, then get a keeper. If not, get the disposable one and gift it to them. 

Hygiene comes into it more importantly afaic.  

 

[Ferdinand]

It will be the same person, so I think the second one above with the one set of spare filters is the one for the first job when blowback etc with a new paint machine is more likely, and see whether he prefers disposables once the technique settles down.

Ferdinand 

Edited September 18, 2017 by Ferdinand

[bassanclan]

I got a 3M 7500 from ebay cheaply. They have replaceable filters and is surprisingly comfortable.

[bassanclan]

I will have to see whether it is better to paint the grooves with a brush or with the spray

[Nickfromwales]

49 minutes ago, bassanclan said:

I will have to see whether it is better to paint the grooves with a brush or with the spray

Brush marks will show through the spray so I'd leave the brush out of it. . 

[Ferdinand]

Reporting back on the Wagner Project Pro 119 from @alexc. That is a £600 machine when new.

 

My handyman did his first ever session earlier this week, and did 3 rooms with 2 coats of Leyland Trade Contract White over new plaster - walls and ceilings. Total surface sprayed was about 140-150 sqm x 2 coats = just under 300 sqm. That took 5 hours of actual spraying using a total of around 27 litres of paint, which had been diluted 10%. I went with Leyaland because current Wickes offers gave a good price of £1.30 per litre for an order of 30 or 60 litres (10l tubs 3 for 2) - about 30% below the best price the Johnstone's Centre could do even with a Trade Account unless I bought pallets of it.

 

That is just about 1 sqm per minute, which is probably slow in the scheme of things - as we ran it at a lower pressure setting than Alex said was possible.

 

So coverage was just on 10 sqm per litre - a little low but one coat was the first one on the plaster.

 

We deliberately took an elapsed day or two to learn the system and work out the tricks and let the knowledge sink in.

 

Masking the rooms was done carefully, and took about half a day, and cleaning the machine afterwards took about an hour.  The estimate is that overall it is probably 3 times quicker if including the masking in this case over using rollers etc. We mixed the tubs for about 15 minutes with a drill paddle immediately before us, and had a bucket of water to submerge the gun when not actively using it - that may be overkill.

 

There was quite a lot of overspray, but that is probably partly down to the learning curve. Masking the floor with building membrane would fix that.

 

i think the easiest mistake to make would be to dispense paint into a bucket which has been used before and not cleaned *really* thorough - the little bits of paint which flake off are exactly the right type to block the gun and waste half an hour cleaning it. We just diluted the new 10l tubs 10% and put the paint pipes in there.

 

Were I using buckets I think I would use a new one every session; the 75p or 99p for the bucket is cheaper than time cleaning out blockages.

 

A good purchase, which will pay for itself within one job just in saved time.

 

And I want Alex's plot moved to Derbyshire to build a house on.

 

Ferdinand

 

 

 

Edited September 21, 2017 by Ferdinand

[Ferdinand]

A couple of supplementary questions:

 

1 - How soon after spraying should a coat be "backrolled" to slightly de-smooth the surface. If it is say a paint that should dry in 2-4 hours, is that something to do immediately, while it is touch-dry etc?

 

2 - I will need to do the same to the skirtings, which we are pre-spraying. Is the a rule of thumb (or intelligent guess) for "back-brushing" sprayed skirtings?

Cheers

 

Ferdinand

 

[Alex C]

Good to hear you got on ok with it. There is a steep learning curve, then it gets really quick to paint. Some of the youtube videos show running the paint through a screen to get lumps out but I found just using paint from a new tub and stirring well worked fine. As you mentioned you don't want to paint out of an old half used tin that has flakes of paint dropping off the rim.

[Ferdinand]

Further comment.

 

When we came to do the topcoat I used a Dulux paint (from Wickes) which did not say spray on the tin, but both Wickes staff and the local Dulux Decorating Centre told me it was sprayable.

 

It was not sprayable - claggy stuff. Dilution did not help. We ended up rollering the topcoats. This was described on the tin as "Matt for Walls and Ceilings".

 

So take care.

Ferdinand

Edited October 15, 2017 by Ferdinand

[Ferdinand]

Can we add here recommendations for paints which do and do not spray OK.

 

 * Interiors

 

For walls, I have tried Leyland Trade Contract White, which is fine.

 

In contrast, the Basic Dulux Matt topcoat was a failure, despite a recommendation from staff at both Wickes and the Dulux Centre that it would be OK. Ended up using a roller.

 

Has anyone sprayed Vapspar White? Valspar mixed?

 

And can anything be recommended for interior woodwork?